Just had to compliment on your car, I'm a bit of a Jaguar nut myself, and I think I could have a valid reason behind the favoritism towards 20w/50 oil.Back in the 60 when Austin released the A10 Mini, the engine used was set up like a motorcycle, the engine shared a sump with the gearbox, and the oil at the time could not stand up to the job. Now Austin could have speced a motorcycle oil, but (at least I think) they didnt want to since it wasnt very professional (its like VW saying its ok it their new car to run an aviation oil, instead creative a VW 54295034850.09 specification). If I remember correctly, Duckhams came to the rescue and invented 20w/50 oil. It was thick enough to protect the high revving A series engine while stand up to the crushing gearbox gears, and not be too restrictive in the winter, which in England happens every 10 minutes. The Austin A10 became the best selling car England made, and due to their service requirements, all service stations had lots of 20w/50 around. However, most British cars (Triumph, Healey, MG, TVR, and Lotus) were small and high revving, and for their cold climate, 20w/50 was an excellent break away for straight 30 and 40 SAE. Even in 1980, MG was still recommending 20w/50.
Its strange how car company nationalities have a common oil. (back in the day) Americans love 10w30, Germans love a 10w/40, English love a 20w/50, Italians like both 10/40 and 20/50...
Back to England, mechanics working on ageing 1275 A series engines and 1498 Triumph engines started realizing their oil pumps favored a light oil, even though the bearings of the 1498s loved something really thick. As for Jag, with the fuel economy switches, it was realized 20/50 was a waste, and 10/40 was fine.
By the 90s, English love with 20w/50 was over. And so was their car industry.
Its strange how car company nationalities have a common oil. (back in the day) Americans love 10w30, Germans love a 10w/40, English love a 20w/50, Italians like both 10/40 and 20/50...
Back to England, mechanics working on ageing 1275 A series engines and 1498 Triumph engines started realizing their oil pumps favored a light oil, even though the bearings of the 1498s loved something really thick. As for Jag, with the fuel economy switches, it was realized 20/50 was a waste, and 10/40 was fine.
By the 90s, English love with 20w/50 was over. And so was their car industry.
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